JP2021063152A - Display body and adhesive sheet - Google Patents

Abstract

To provide an adhesive sheet that can improve designability of a display body, and a display body having improved designability.SOLUTION: An adhesive sheet 1 has an adhesive layer 11 for bonding one display body constituent member 21 to another display body constituent member 22. The adhesive layer 11 has a color difference ΔE* of less than 95 from a completely white color that is defined by CIE1976 L*a*b* color system. The adhesive layer 11 has a total light transmittance of 10% or more.SELECTED DRAWING: Figure 1

Description

The present invention relates to a display body and an adhesive sheet used for the display body.

In recent years, display devices (displays) such as televisions, monitors for personal computers, digital signage, smartphones, tablet terminals, and the like use image display devices such as liquid crystal display devices and organic electroluminescence (organic EL) devices. There are many things.

In the above-mentioned display body, when the display body is turned off, it may be required to give a sense of unity with a peripheral member of the display body, for example, a frame material, and improve the design. For that purpose, it is conceivable to color the display body. A technique relating to coloring of a display body is disclosed in, for example, Patent Document 1.

Japanese Unexamined Patent Publication No. 2005-82634

However, since the purpose of coloring the adhesive sheet disclosed in Patent Document 1 is light-shielding property and light-concealing property, the visibility of the displayed image is improved when used on the viewer side rather than the liquid crystal module or the organic EL module. Cannot be secured.

The present invention has been made in view of the above-mentioned actual conditions, and an object of the present invention is to provide an adhesive sheet capable of improving the design of a display body and a display body having an improved design.

In order to achieve the above object, firstly, the present invention is an adhesive sheet provided with an adhesive layer for adhering one display body constituent member and another display body constituent member, and is CIE1976L *. The color difference ΔE * from the completely white color of the pressure-sensitive adhesive layer defined by the a * b * color system is less than 95, and the total light transmittance of the pressure-sensitive adhesive layer is 10% or more. Provided is a characteristic adhesive sheet (Invention 1).

In the above invention (Invention 1), since the color difference ΔE * of the pressure-sensitive adhesive layer is as described above, the appearance is harmonized with the white peripheral member when the display body is turned off, and the design is improved. .. Further, in the above invention (Invention 1), since the total light transmittance of the pressure-sensitive adhesive layer is as described above, the visibility of the image / video can be ensured when the display body is lit.

In the above invention (Invention 1), the haze value of the pressure-sensitive adhesive layer is preferably 0.5% or more and 100% or less (Invention 2).

In the above inventions (Inventions 1 and 2), it is preferable that the pressure-sensitive adhesive layer is made of a pressure-sensitive adhesive containing a white colorant (Invention 3).

In the above inventions (Inventions 1 to 3), the content of the white colorant in the pressure-sensitive adhesive is preferably 0.01% by mass or more and 50% by mass or less (Invention 4).

In the above inventions (Inventions 1 to 4), the pressure-sensitive adhesive is preferably an acrylic pressure-sensitive adhesive (Invention 5).

In the above inventions (Inventions 1 to 5), the pressure-sensitive adhesive crosslinks a pressure-sensitive adhesive composition containing at least a (meth) acrylic acid ester polymer (A), a cross-linking agent (B), and a white colorant (C). (Invention 6).

In the above inventions (Inventions 1 to 6), it is preferable to provide two release sheets and the pressure-sensitive adhesive layer sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets (invention). 7).

Secondly, the present invention includes one display body component, another display body component, and an adhesive layer for adhering the one display body component and the other display body components to each other. Provided is a display body, wherein the pressure-sensitive adhesive layer is formed from the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheets (Inventions 1 to 7) (Invention 8).

In the above invention (Invention 8), it is preferable that at least one of the one display body constituent member and the other display body constituent member has a step on the surface on the side to be bonded by the pressure-sensitive adhesive layer (Invention 9). ).

In the above inventions (Inventions 8 and 9), it is preferable to have a white peripheral member (Invention 10).

According to the adhesive sheet according to the present invention, the design of the display body can be improved. In addition, the display body according to the present invention has improved design.

It is sectional drawing of the pressure-sensitive adhesive sheet which concerns on one Embodiment of this invention. It is sectional drawing of the display body which concerns on one Embodiment of this invention. It is a top view of the display body which has a frame material which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described.
[Adhesive sheet]
The pressure-sensitive adhesive sheet according to an embodiment of the present invention includes a pressure-sensitive adhesive layer for adhering one display body component and another display body component, preferably one side of the pressure-sensitive adhesive layer. Alternatively, release sheets are laminated on both sides. The display body and the display body constituent members will be described later.

FIG. 1 shows a specific configuration as an example of the pressure-sensitive adhesive sheet according to the present embodiment.
As shown in FIG. 1, the adhesive sheet 1 is sandwiched between the two release sheets 12a and 12b and the two release sheets 12a and 12b so as to be in contact with the release surfaces of the two release sheets 12a and 12b. It is composed of a pressure-sensitive adhesive layer 11. The peeling surface of the release sheet in the present specification means a surface of the release sheet that has peelability, and includes both a surface that has been peeled and a surface that exhibits peelability without peeling. ..

1. 1. Each member 1-1. Adhesive layer The adhesive layer 11 of the adhesive sheet 1 according to the present embodiment has a color difference ΔE * from perfect white defined by the CIE1976L * a * b * color system of less than 95, and has a total light transmittance. Is 10% or more.

なお、本明細書における明度Ｌ*、色度ａ*およびｂ*の測定方法（反射光測定）は、後述する試験例に示す通りである。 The perfect white color defined by the CIE1976 L * a * b * color system has a lightness L * of 100, a chromaticity a * of 0, and a chromaticity b * of 0. Therefore, when the measured value of the lightness L * for the pressure-sensitive adhesive layer 11 is L * M, the measured value of the chromaticity a * is a * M, and the measured value of b * is b * M, it is completely white. The color difference ΔE * is calculated by the following formula (I).

The measurement method (reflected light measurement) of the brightness L *, the chromaticity a * and the b * in the present specification is as shown in the test example described later.

In the pressure-sensitive adhesive sheet 1 according to the present embodiment, since the color difference ΔE * of the pressure-sensitive adhesive layer 11 is as described above, when the display body is turned off, white peripheral members such as a white frame material, a white wall, and a white printed portion are used. The appearance is harmonized with the above, and the design is improved. The white color of the peripheral members does not have to be the above-mentioned "perfect white color".

Further, in the pressure-sensitive adhesive sheet 1 according to the present embodiment, since the total light transmittance of the pressure-sensitive adhesive layer 11 is 10% or more, the visibility of images and videos can be ensured when the display body is lit. The total light transmittance in the present specification is a value measured in accordance with JIS K7361-1: 1997.

The color difference ΔE * needs to be less than 95, preferably 80 or less, more preferably 60 or less, and particularly 40 or less, from the viewpoint of appearance harmony with the white peripheral member. It is preferable, and more preferably 35 or less. The lower limit of the color difference ΔE * is not particularly limited, and the smallest value is 0. However, considering the relationship with the total light transmittance, it is preferably 1 or more, and more preferably 5 or more. In particular, it is preferably 10 or more, and more preferably 20 or more.

The lightness L * M of the pressure-sensitive adhesive layer 11 is preferably 3 or more, more preferably 9 or more, particularly preferably 50 or more, and further preferably 65 or more. The brightness L * M is preferably 100 or less, more preferably 90 or less, particularly preferably 83 or less, and further preferably 80 or less. The absolute value of the chromaticity a * M of the pressure-sensitive adhesive layer 11 is preferably 0 or more, particularly preferably 0.1 or more, and further preferably 0.5 or more. The absolute value of the chromaticity a * M is preferably 10 or less, more preferably 5 or less, particularly preferably 2 or less, and further preferably 1.5 or less. .. The absolute value of the chromaticity b * M of the pressure-sensitive adhesive layer 11 is preferably 0 or more, and particularly preferably 0.1 or more. The absolute value of the chromaticity b * M is preferably 10 or less, more preferably 5 or less, particularly preferably 2 or less, and further preferably 1.5 or less. .. As a result, the color difference ΔE * and the total light transmittance can be easily satisfied, and the display body has a preferable color when the display body is turned off.

The total light transmittance of the pressure-sensitive adhesive layer 11 needs to be 10% or more, preferably 20% or more, and more preferably 30% or more, from the viewpoint of visibility of images and videos. In particular, it is preferably 40% or more, and more preferably 45% or more. The upper limit of the total light transmittance is usually 100% or less, and in consideration of the relationship with the color difference ΔE *, it is preferably 95% or less, more preferably 90% or less, and particularly 80%. It is preferably less than or equal to, more preferably 70% or less, and most preferably 65% or less.

The haze value of the pressure-sensitive adhesive layer 11 is preferably 0.5% or more, more preferably 5% or more, particularly preferably 15% or more, and further preferably 60% or more. , 90% or more is most preferable. This makes it easier to satisfy the color difference ΔE *, and makes it easier to give the obtained display body a sense of unity with the white peripheral members. The upper limit of the haze value of the pressure-sensitive adhesive layer 11 is not particularly limited, but is preferably 100% or less, more preferably 99.9% or less, and particularly preferably 99.8% or less. Further, it is preferably 99.4% or less. The haze value in the present specification is a value measured according to JIS K7136: 2000.

The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 11 preferably contains a white-based colorant, and by appropriately selecting the type and content of the white-based colorant, the above-mentioned color difference ΔE * and total light transmittance (further). Haze value) can be achieved.

The white colorant may be mainly a pigment or a dye. The pigment may be an inorganic pigment or an organic pigment. From the viewpoint of the durability of the obtained pressure-sensitive adhesive, inorganic pigments are preferable.

The white colorant preferably contains an inorganic pigment such as titanium oxide, zinc oxide, calcium carbonate, or aluminum oxide, and is oxidized from the viewpoint of easily maintaining a high total light transmittance even when ΔE * is low. Titanium and zinc oxide are more preferable, and titanium oxide is particularly preferable. These inorganic pigments may be subjected to surface treatment such as organic treatment, silicone treatment, and alumina treatment. The above-mentioned inorganic pigment may be used alone or in combination of two or more.

Further, the white colorant may contain colorless and transparent fine particles such as silica together with the inorganic pigment. This makes it easier to obtain an appropriate white color. In this case, the content of the colorless transparent fine particles is preferably 0.01 to 50% by mass, more preferably 0.1 to 30% by mass, and particularly 1 to 20% by mass in the white colorant. It is preferably abundant, and more preferably 5 to 10% by mass.

The mode diameter (mode diameter) of the white colorant is preferably 2 nm or more, more preferably 10 nm or more, particularly preferably 100 nm or more, and further preferably 200 nm or more. This makes it easier to satisfy the above-mentioned color difference ΔE *. The mode diameter is preferably 3000 nm or less, more preferably 1000 nm or less, particularly preferably 800 nm or less, and further preferably 600 nm or less. This makes it easier to satisfy the above-mentioned total light transmittance.

The median diameter (D50) of the white colorant is preferably 2 nm or more, more preferably 10 nm or more, particularly preferably 100 nm or more, and further preferably 200 nm or more. This makes it easier to satisfy the above-mentioned color difference ΔE *. The median diameter is preferably 3000 nm or less, more preferably 1000 nm or less, particularly preferably 800 nm or less, and further preferably 600 nm or less. This makes it easier to satisfy the above-mentioned total light transmittance.

The mode diameter and median diameter of the white colorant in the present specification are values measured by a dynamic light scattering method.

The content of the white colorant in the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 11 is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and particularly 1% by mass or more. It is more preferable that there is, and more preferably 3% by mass or more. As a result, the above-mentioned color difference ΔE * can be easily satisfied without making the pressure-sensitive adhesive layer too thick. The content is preferably 50% by mass or less, more preferably 30% by mass or less, particularly preferably 20% by mass or less, and further preferably 15% by mass or less. More preferably, it is preferably 8% by mass or less, considering the viewpoint that the pressure-sensitive adhesive layer is thin and the step-following property is also excellent. This makes it easier to satisfy the above-mentioned total light transmittance.

The thickness of the pressure-sensitive adhesive layer 11 is preferably 3 μm or more, and more preferably 10 μm or more, as a lower limit value from the viewpoint that the above-mentioned optical physical characteristics are easily satisfied in relation to the content of the white colorant. In particular, it is preferably 20 μm or more, and from the viewpoint of further improving the step followability, it is preferably 40 μm or more.

The thickness of the pressure-sensitive adhesive layer 11 is preferably 3000 μm or less, more preferably 1000 μm or less, particularly preferably 500 μm or less, and further preferably 300 μm or less as an upper limit value. When the upper limit of the thickness of the pressure-sensitive adhesive layer 11 is the above, the above-mentioned optical physical characteristics are easily satisfied in relation to the content of the white colorant. In addition, appearance defects due to push marks and the like are less likely to occur.

The pressure-sensitive adhesive layer 11 may be formed as a single layer, or may be formed by laminating a plurality of layers. The thickness of the pressure-sensitive adhesive layer 11 in the present specification is a value measured according to JIS K7130.

The type of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 according to the present embodiment is not particularly limited, and for example, an acrylic pressure-sensitive adhesive, a polyester-based pressure-sensitive adhesive, a polyurethane-based pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, and a silicone. Any of the adhesives may be used. Further, the pressure-sensitive adhesive may be an emulsion type, a solvent type or a solvent-free type, and may be either a crosslinked type or a non-crosslinked type. Among them, an acrylic pressure-sensitive adhesive having excellent adhesive physical properties, optical properties, and the like is preferable.

Further, the acrylic pressure-sensitive adhesive may be an active energy ray-curable adhesive or an active energy ray non-curable adhesive. Further, as the acrylic pressure-sensitive adhesive, a cross-linked type is preferable, and a heat-cross-linked type is more preferable.

Specifically, the pressure-sensitive adhesive is a pressure-sensitive composition containing at least a (meth) acrylic acid ester polymer (A), a cross-linking agent (B), and a white colorant (C) (hereinafter, "adhesiveness"). It may be referred to as "composition P"), and it is preferably obtained by cross-linking. When the pressure-sensitive adhesive is an active energy ray-curable pressure-sensitive adhesive, the pressure-sensitive adhesive composition P preferably further contains an active energy ray-curable component (D).

The pressure-sensitive adhesive obtained from such a pressure-sensitive adhesive composition P can exhibit excellent optical properties, adhesive strength, durability (step followability under high temperature and high humidity conditions) and the like. In addition, in this specification, (meth) acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms. In addition, the concept of "polymer" shall be included in "polymer".

(1) Ingredients of Adhesive Composition (1-1) (Meta) Acrylic Ester Polymer (A)
The (meth) acrylic acid ester polymer (A) in the present embodiment contains a reactive group-containing monomer having a reactive group in the molecule that reacts with the cross-linking agent (B) as a monomer unit constituting the polymer. Is preferable. The reactive group derived from this reactive group-containing monomer reacts with the cross-linking agent (B) to form a cross-linked structure (three-dimensional network structure), and a pressure-sensitive adhesive having a desired cohesive force can be obtained.

Examples of the reactive group-containing monomer include a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer), a monomer having a carboxy group in the molecule (carboxy group-containing monomer), and a monomer having an amino group in the molecule (amino group-containing monomer). ) Etc. are preferably mentioned. Among these, a hydroxyl group-containing monomer or a carboxy group-containing monomer having excellent reactivity with the cross-linking agent (B) is preferable, and the hydroxyl group-containing monomer and the carboxy group-containing monomer may be used in combination.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and (meth). ) Hydroxyalkyl esters of (meth) acrylic acid such as 3-hydroxybutyl acrylate and 4-hydroxybutyl (meth) acrylic acid can be mentioned. Among them, hydroxy having 1 to 4 carbon atoms is considered from the viewpoint of the reactivity of the obtained (meth) acrylic acid ester polymer (A) with the cross-linking agent (B) of the hydroxyl group and the copolymerizability with other monomers. A (meth) acrylic acid hydroxyalkyl ester having an alkyl group is preferable. Specifically, for example, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate and the like are preferable, and 2-hydroxyethyl acrylate or 4-hydroxybutyl acrylate are particularly preferable. Be done. These may be used alone or in combination of two or more.

Examples of the carboxy group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Of these, acrylic acid is preferable from the viewpoint of reactivity of the obtained (meth) acrylic acid ester polymer (A) with the cross-linking agent (B) of the carboxy group and copolymerizability with other monomers. These may be used alone or in combination of two or more.

Examples of the amino group-containing monomer include aminoethyl (meth) acrylate and n-butylaminoethyl (meth) acrylate. These may be used alone or in combination of two or more.

The (meth) acrylic acid ester polymer (A) preferably contains a reactive group-containing monomer as a lower limit value of 1% by mass or more, and particularly 5% by mass or more, as a monomer unit constituting the polymer. It is preferable to contain 10% by mass or more, and when the reactive group-containing monomer is only a hydroxyl group-containing monomer, it is preferably contained in an amount of 15% by mass or more, particularly preferably 20% by mass or more. preferable. Further, the (meth) acrylic acid ester polymer (A) preferably contains a reactive group-containing monomer as an upper limit value of 40% by mass or less, particularly 30% by mass or less, as a monomer unit constituting the polymer. It is preferably contained, and more preferably 25% by mass or less. When the (meth) acrylic acid ester polymer (A) contains the reactive group-containing monomer in the above amount as the monomer unit, a good crosslinked structure is formed in the obtained pressure-sensitive adhesive, and a desired cohesive force can be obtained. Further, the dispersibility of the white colorant (C) in the pressure-sensitive adhesive tends to be good, and the obtained pressure-sensitive adhesive has good reproducibility and uniformity of the above-mentioned optical physical properties, and the above-mentioned color difference ΔE * Will be easier to meet.

Further, it is also preferable that the (meth) acrylic acid ester polymer (A) does not contain a carboxy group-containing monomer as a monomer unit constituting the polymer. Since the carboxy group is an acid component, since it does not contain a carboxy group-containing monomer, a transparent conductive film such as tin-doped indium oxide (ITO) or a metal film, which causes a problem due to the acid, is attached to the adhesive. Even if it exists, those defects (corrosion, change in resistance value, etc.) due to acid can be suppressed. However, it is permissible to contain a predetermined amount of the carboxy group-containing monomer so as not to cause such a problem. Specifically, in the (meth) acrylic acid ester polymer (A), the carboxy group-containing monomer is contained in an amount of 0.1% by mass or less, preferably 0.01% by mass or less, more preferably 0.001 as a monomer unit. It is permissible to contain in an amount of mass% or less.

The (meth) acrylic acid ester polymer (A) preferably contains a (meth) acrylic acid alkyl ester as a monomer unit constituting the polymer. Thereby, good adhesiveness can be exhibited. The alkyl group may be linear or branched chain.

As the (meth) acrylic acid alkyl ester, a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms is preferable from the viewpoint of adhesiveness. Examples of the (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms include methyl (meth) acrylic acid, ethyl (meth) acrylic acid, propyl (meth) acrylic acid, and n- (meth) acrylic acid. Butyl, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n-decyl (meth) acrylate, (meth) acrylate Examples thereof include n-dodecyl, myristyl (meth) acrylate, palmityl (meth) acrylate, and stearyl (meth) acrylate. Among them, (meth) acrylic acid ester having 1 to 8 carbon atoms of the alkyl group is preferable from the viewpoint of further improving the adhesiveness, and methyl (meth) acrylate, n-butyl (meth) acrylate or (meth) acrylic. 2-Ethylhexyl acrylate is particularly preferred, and methyl methacrylate, n-butyl acrylate or 2-ethylhexyl acrylate is even more preferred. These may be used alone or in combination of two or more.

The (meth) acrylic acid ester polymer (A) preferably contains (meth) acrylic acid alkyl ester in an amount of 40% by mass or more, and particularly 50% by mass or more, as a monomer unit constituting the polymer. It is preferable, and it is preferable that the content is 60% by mass or more. When the lower limit of the content of the (meth) acrylic acid alkyl ester is as described above, the (meth) acrylic acid ester polymer (A) can exhibit suitable tackiness. Further, the dispersibility of the white colorant (C) in the adhesive tends to be good, and the (meth) acrylic acid ester polymer (A) is suppressed from impairing the desired adhesiveness. As a result, the obtained adhesive can exhibit suitable adhesiveness, and the reproducibility and uniformity of the above-mentioned optical physical characteristics become good, and the above-mentioned color difference ΔE * can be easily satisfied. Further, the (meth) acrylic acid ester polymer (A) preferably contains 99% by mass or less of the (meth) acrylic acid alkyl ester as a monomer unit constituting the polymer, and preferably contains 95% by mass or less. Is more preferable, and it is particularly preferable to contain 90% by mass or less, and further preferably 85% by mass or less. When the upper limit of the content of the (meth) acrylic acid alkyl ester is as described above, a suitable amount of another monomer component such as a reactive functional group-containing monomer is introduced into the (meth) acrylic acid ester polymer (A). be able to.

The (meth) acrylic acid ester polymer (A) preferably contains a monomer having an alicyclic structure in the molecule (alicyclic structure-containing monomer) as a monomer unit constituting the polymer. Since the alicyclic structure-containing monomer is bulky, it is presumed that the presence of the monomer in the polymer widens the distance between the polymers, and the obtained pressure-sensitive adhesive can be made excellent in flexibility. .. As a result, the adhesive has excellent step followability.

The alicyclic structure carbon ring in the alicyclic structure-containing monomer may have a saturated structure or may have an unsaturated bond as a part. Further, the alicyclic structure may be a monocyclic alicyclic structure or a polycyclic alicyclic structure such as two rings or three rings. From the viewpoint of making the distance between the obtained (meth) acrylic acid ester polymers (A) appropriate and imparting high stress relaxation property to the pressure-sensitive adhesive, the alicyclic structure is a polycyclic alicyclic structure. Polycyclic structure) is preferable. Further, in consideration of the compatibility between the (meth) acrylic acid ester polymer (A) and other components, the polycyclic structure is particularly preferably bicyclic to tetracyclic. Further, from the viewpoint of imparting stress relaxation property as described above, the number of carbon atoms in the alicyclic structure (referring to the total number of carbon atoms in the portion forming the ring, and when a plurality of rings exist independently) , The total number of carbon atoms) is usually preferably 5 or more, and particularly preferably 7 or more. On the other hand, the upper limit of the number of carbon atoms in the alicyclic structure is not particularly limited, but from the viewpoint of compatibility as described above, it is preferably 15 or less, and particularly preferably 10 or less.

Specific examples of the alicyclic structure-containing monomer include cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, adamantyl (meth) acrylate, isobornyl (meth) acrylate, and (meth) acrylic. Dicyclopentenyl acid, dicyclopentenyloxyethyl (meth) acrylate, etc., among others, dicyclopentanyl (meth) acrylate (carbon number of alicyclic structure:) which exhibits better step followability: 10), adamantyl (meth) acrylate (carbon number of alicyclic structure: 10) or isobornyl (meth) acrylate (carbon number of carbon number of alicyclic structure: 7) is preferable, and isobornyl (meth) acrylate is particularly preferable. Further, isobornyl acrylate is preferable. These may be used individually by 1 type, and may be used in combination of 2 or more type.

When the (meth) acrylic acid ester polymer (A) contains an alicyclic structure-containing monomer as a monomer unit constituting the polymer, it preferably contains 1% by mass or more of the alicyclic structure-containing monomer. In particular, it is preferably contained in an amount of 4% by mass or more, and more preferably 8% by mass or more. Further, the (meth) acrylic acid ester polymer (A) preferably contains 30% by mass or less of an alicyclic structure-containing monomer, and particularly 22% by mass or less, as a monomer unit constituting the polymer. It is preferable that the content is 14% by mass or less. When the content of the alicyclic structure-containing monomer is in the above range, the obtained adhesive has more excellent step-following property and has more excellent adhesive force to plastic.

Further, it is also preferable that the (meth) acrylic acid ester polymer (A) contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer. By allowing a nitrogen atom-containing monomer to be present in the polymer as a constituent unit, a predetermined polarity is imparted to the pressure-sensitive adhesive, and the adhesive has excellent affinity for an adherend having a certain degree of polarity such as glass. Can be. As the nitrogen atom-containing monomer, a monomer having a nitrogen-containing heterocycle is preferable from the viewpoint of imparting appropriate rigidity to the (meth) acrylic acid ester polymer (A). Further, from the viewpoint of increasing the degree of freedom of the portion derived from the nitrogen atom-containing monomer in the higher-order structure of the constituent pressure-sensitive adhesive, the nitrogen atom-containing monomer forms the (meth) acrylic acid ester polymer (A). It is preferable that no reactive unsaturated double bond group is contained other than one polymerizable group used for the polymerization of.

Examples of the monomer having a nitrogen-containing heterocycle include N- (meth) acryloyl morpholine, N-vinyl-2-pyrrolidone, N- (meth) acryloyl pyrrolidone, N- (meth) acryloyl piperidine, and N- (meth) acryloyl. Pyrrolidine, N- (meth) acryloyl azylidine, aziridinyl ethyl (meth) acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, N-vinylphthalimide, etc. Among them, N- (meth) acryloylmorpholin, which exhibits more excellent adhesive strength, is preferable, and N-acryloylmorpholin is particularly preferable. These may be used individually by 1 type, and may be used in combination of 2 or more type.

When the (meth) acrylic acid ester polymer (A) contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer, the (meth) acrylic acid ester polymer (A) preferably contains the nitrogen atom-containing monomer in an amount of 1% by mass or more, particularly 4% by mass. It is preferably contained in an amount of% or more, and more preferably 8% by mass or more. Further, the (meth) acrylic acid ester polymer (A) preferably contains the nitrogen atom-containing monomer in an amount of 20% by mass or less, particularly 16% by mass or less, as a monomer unit constituting the polymer. It is preferable, and it is preferable that the content is 12% by mass or less. When the content of the nitrogen atom-containing monomer is within the above range, the obtained pressure-sensitive adhesive can sufficiently exert excellent adhesive strength to glass.

If desired, the (meth) acrylic acid ester polymer (A) may contain another monomer as a monomer unit constituting the polymer. As the other monomer, a monomer containing no reactive functional group is preferable so as not to inhibit the above-mentioned action of the reactive functional group-containing monomer. Examples of such monomers include (meth) acrylic acid alkoxyalkyl esters such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, vinyl acetate, and styrene. These may be used alone or in combination of two or more.

The (meth) acrylic acid ester polymer (A) is preferably a linear polymer. Since it is a linear polymer, entanglement of molecular chains is likely to occur, and improvement in cohesive force can be expected. Therefore, the obtained adhesive tends to exhibit a suitable gel fraction, adhesive strength, and the like, and tends to have excellent step followability under high temperature and high humidity conditions.

Further, the (meth) acrylic acid ester polymer (A) is preferably a solution polymer obtained by a solution polymerization method. Since it is a solution polymer, it becomes easy to obtain a polymer having a high molecular weight, and improvement in cohesive force can be expected. Therefore, the obtained adhesive tends to exhibit a suitable gel fraction, adhesive strength, and the like, and tends to have excellent step followability under high temperature and high humidity conditions.

The polymerization mode of the (meth) acrylic acid ester polymer (A) may be a random copolymer or a block copolymer.

The weight average molecular weight of the (meth) acrylic ester polymer (A) is preferably 200,000 or more, particularly preferably 300,000 or more, and further preferably 400,000 or more as the lower limit value. When the lower limit of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is as described above, the gel fraction and the storage elastic modulus of the obtained adhesive tend to be suitable, and under high temperature and high humidity conditions. The step followability in the above is improved. Further, the white colorant (C) tends to have good dispersibility in the pressure-sensitive adhesive, and therefore, the obtained pressure-sensitive adhesive has good reproducibility and uniformity of the above-mentioned optical physical properties, and has been described above. It becomes easier to satisfy the color difference ΔE *.

The weight average molecular weight of the (meth) acrylic acid ester polymer (A) is preferably 2 million or less, more preferably 1.5 million or less, and particularly preferably 1 million or less, as an upper limit value. Further, it is preferably 800,000 or less. When the upper limit of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is as described above, the gel fraction and the storage elastic modulus of the obtained adhesive tend to be suitable, and the initial step followability Becomes better. The weight average molecular weight in the present specification is a standard polystyrene-equivalent value measured by a gel permeation chromatography (GPC) method.

In the adhesive composition P, the (meth) acrylic acid ester polymer (A) may be used alone or in combination of two or more.

(1-2) Crosslinking agent (B)
The cross-linking agent (B) can cross-link the (meth) acrylic acid ester polymer (A) by heating the adhesive composition P to form a three-dimensional network structure satisfactorily. As a result, the cohesive force of the obtained adhesive is improved, and the step followability under high temperature and high humidity conditions is excellent.

The cross-linking agent (B) may be any as long as it reacts with the reactive group of the (meth) acrylic acid ester polymer (A). For example, an isocyanate-based cross-linking agent, an epoxy-based cross-linking agent, and an amine-based cross-linking agent. , Melamine-based cross-linking agent, aziridine-based cross-linking agent, hydrazine-based cross-linking agent, aldehyde-based cross-linking agent, oxazoline-based cross-linking agent, metal alkoxide-based cross-linking agent, metal chelate-based cross-linking agent, metal salt-based cross-linking agent, ammonium salt-based cross-linking agent, etc. Can be mentioned. Among the above, it is preferable to use an isocyanate-based cross-linking agent having excellent reactivity with the reactive group of the (meth) acrylic acid ester polymer (A). The cross-linking agent (B) may be used alone or in combination of two or more.

The isocyanate-based cross-linking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanates, and alicyclic polyisocyanates such as hydrogenated diphenylmethane diisocyanate. , And their biurets, isocyanurates, and adducts, which are reactants with low molecular weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Of these, trimethylolpropane-modified aromatic polyisocyanates, particularly trimethylolpropane-modified tolylene diisocyanate and trimethylolpropane-modified xylylene diisocyanate, are preferable from the viewpoint of reactivity with hydroxyl groups.

The content of the cross-linking agent (B) in the adhesive composition P is preferably 0.01 part by mass or more with respect to 100 parts by mass of the (meth) acrylic acid ester polymer (A), and in particular, 0. It is preferably 05 parts by mass or more, and more preferably 0.1 parts by mass or more. The content is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, particularly preferably 1 part by mass or less, and further preferably 0.4 parts by mass or less. Is preferable. When the content of the cross-linking agent (B) is within the above range, the obtained adhesive exhibits good cohesive force, and the values such as gel fraction and adhesive force tend to be suitable, and the temperature and humidity conditions are high. It becomes excellent due to the step followability underneath.

(1-3) White colorant (C)
The white colorant (C) is the white colorant described above. The specific types and contents are as described above.

(1-4) Active energy ray-curable component (D)
In a pressure-sensitive adhesive obtained by cross-linking a pressure-sensitive adhesive composition P with active energy ray-curable, the active energy ray-curable components (D) are polymerized with each other, and the polymerized active energy ray-curable component (D) is It is presumed that the (meth) acrylic acid ester polymer (A) is entangled in the crosslinked structure (three-dimensional network structure). The pressure-sensitive adhesive having such a high-order structure is particularly excellent in step followability under high temperature and high humidity conditions.

The active energy ray-curable component (D) is not particularly limited as long as it is a component that is cured by irradiation with active energy rays and obtains the above effects, and may be any of monomers, oligomers, and polymers, and they may be used. May be a mixture of. Among them, a polyfunctional acrylate-based monomer having excellent step followability under high temperature and high humidity conditions can be preferably mentioned.

Examples of the polyfunctional acrylate-based monomer include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and polyethylene glycol di (meth) acrylate. , Neopentyl glycol adipate di (meth) acrylate, neopentyl glycol di (meth) acrylate of hydroxypivalate, dicyclopentanyl di (meth) acrylate, tricyclodecanedimethanol (meth) acrylate, caprolactone-modified dicyclopentenyldi ( Meta) acrylate, ethylene oxide modified di (meth) acrylate, di (acryloxyethyl) isocyanurate, allylated cyclohexyl di (meth) acrylate, ethoxylated bisphenol A diacrylate, 9,9-bis [4- (2-) Bifunctional type such as acryloyloxyethoxy) phenyl] fluorene; trimethylpropantri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid-modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate , Protinoxide-modified trimethylolpropane tri (meth) acrylate, tris (acryloxyethyl) isocyanurate, ε-caprolactone-modified tris- (2- (meth) acryloxyethyl) isocyanurate, etc. Four-functional types such as meta) acrylate and pentaerythritol tetra (meth) acrylate; pentafunctional type such as propionic acid-modified dipentaerythritol penta (meth) acrylate; dipentaerythritol hexa (meth) acrylate and caprolactone-modified dipentaerythritol hexa ( Examples thereof include a hexafunctional type such as meta) acrylate. These may be used individually by 1 type, and may be used in combination of 2 or more type. Further, from the viewpoint of compatibility with the (meth) acrylic acid ester polymer (A), the polyfunctional acrylate-based monomer preferably has a molecular weight of less than 1000.

When the adhesive composition P contains the active energy ray-curable component (D), the content of the active energy ray-curable component (D) in the adhesive composition P is the (meth) acrylic acid ester polymer (meth). A) With respect to 100 parts by mass, the lower limit is preferably 1 part by mass or more, particularly preferably 3 parts by mass or more, and further preferably 4 parts by mass or more. On the other hand, the content is preferably 30 parts by mass or less, particularly preferably 20 parts by mass or less, and 14 parts by mass or less as an upper limit value from the viewpoint of the adhesive strength of the pressure-sensitive adhesive after the active energy ray curing. It is more preferable that the amount is 9 parts by mass or less from the viewpoint of facilitating the exertion of higher adhesive strength. When the content of the active energy ray-curable component (D) is within the above range, the pressure-sensitive adhesive after the active energy ray-curing tends to have suitable values such as gel fraction and adhesive strength, and is under high temperature and high humidity conditions. It becomes excellent due to the step followability underneath.

(1-5) Photopolymerization Initiator (E)
When ultraviolet rays are used as the active energy rays for curing the adhesive composition P, the adhesive composition P preferably further contains a photopolymerization initiator (E). By containing the photopolymerization initiator (E) in this way, the active energy ray-curable component (D) can be efficiently polymerized, and the polymerization curing time and the irradiation amount of the active energy rays can be reduced. it can.

Examples of such a photopolymerization initiator (E) include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, and 2,2-dimethoxy. -2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenylketone, 2-methyl-1- [4- (Methylthio) phenyl] -2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylamino Benzophenone, Dichlorobenzophenone, 2-Methylanthraquinone, 2-Ethylanthraquinone, 2-Turrary-butylanthraquinone, 2-Aminoanthraquinone, 2-Methylthioxanthone, 2-Ethylthioxanthone, 2-Chlorothioxanthone, 2,4-dimethylthioxanthone, 2 , 4-Diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoic acid ester, oligo [2-hydroxy-2-methyl-1 [4- (1-methylvinyl) phenyl] propanone], 2,4 , 6-trimethylbenzoyl-diphenyl-phosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide and the like. These may be used alone or in combination of two or more.

When the adhesive composition P contains the photopolymerization initiator (E), the content of the photopolymerization initiator (E) in the adhesive composition P is 100 parts by mass of the active energy ray-curable component (D). On the other hand, the lower limit value is preferably 0.1 part by mass or more, particularly preferably 1 part by mass or more, and further preferably 5 parts by mass or more. Further, the upper limit value is preferably 30 parts by mass or less, particularly preferably 20 parts by mass or less, and further preferably 12 parts by mass or less.

(1-6) Various Additives The adhesive composition P contains various additives usually used for acrylic pressure-sensitive adhesives, such as silane coupling agents, rust preventives, ultraviolet absorbers, and antistatic agents, if desired. , Antistatic agents, light stabilizers, softeners, refractive index adjusters and the like can be added. The polymerization solvent and the diluting solvent described later are not included in the additives constituting the adhesive composition P.

The adhesive composition P preferably contains a silane coupling agent among the above. As a result, regardless of whether the adherend is a plastic plate or a glass member, the adhesion to the adherend is improved, and the step followability under high temperature and high humidity conditions is further improved. ..

The silane coupling agent is an organosilicon compound having at least one alkoxysilyl group in the molecule, which has good compatibility with the (meth) acrylic acid ester polymer (A) and has light transmittance. preferable.

Examples of such a silane coupling agent include polymerizable unsaturated group-containing silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacrypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 2-(. 3,4-Epoxycyclohexyl) Silicon compounds having an epoxy structure such as ethyltrimethoxysilane, mercapto group-containing silicon compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropyldimethoxymethylsilane , 3-Aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane and other amino group-containing silicon compounds, 3-Chloropropyltrimethoxysilane, 3-isocyanuppropyltriethoxysilane, or at least one of these, and alkyl group-containing silicon compounds such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, and ethyltrimethoxysilane. Examples thereof include a condensate of. These may be used individually by 1 type, and may be used in combination of 2 or more type.

The content of the silane coupling agent in the adhesive composition P is preferably 0.01 part by mass or more, particularly 0.05 by mass, based on 100 parts by mass of the (meth) acrylic acid ester polymer (A). It is preferably parts by mass or more, and more preferably 0.1 parts by mass or more. The content is preferably 1 part by mass or less, particularly preferably 0.5 part by mass or less, and further preferably 0.3 part by mass or less.

(2) Preparation of Adhesive Composition The adhesive composition P produced a (meth) acrylic acid ester polymer (A), and the obtained (meth) acrylic acid ester polymer (A) and a cross-linking agent ( It can be produced by mixing B) and a white colorant (C) and, if desired, adding an active energy ray-curable component (D), a photopolymerization initiator (E), an additive and the like.

The (meth) acrylic acid ester polymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer by a usual radical polymerization method. The polymerization of the (meth) acrylic acid ester polymer (A) is preferably carried out by a solution polymerization method using a polymerization initiator, if desired. However, the present invention is not limited to this, and polymerization may be carried out without a solvent. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone and the like, and two or more of them may be used in combination.

Examples of the polymerization initiator include azo compounds and organic peroxides, and two or more of them may be used in combination. Examples of the azo compound include 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane1-carbonitrile), and 2, , 2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2'-azobis (2-methylpropionate) 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis (2-hydroxymethylpropionitrile), 2,2'-azobis [2- (2-imidazolin-2-yl)) Propane] and the like.

Examples of the organic peroxide include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxy dicarbonate, di-n-propyl peroxy dicarbonate, and di (2-ethoxyethyl) peroxy. Examples thereof include dicarbonate, t-butylperoxyneodecanoate, t-butylperoxyvivarate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, and diacetyl peroxide.

In the above polymerization step, the weight average molecular weight of the obtained polymer can be adjusted by adding a chain transfer agent such as 2-mercaptoethanol.

Once the (meth) acrylic acid ester polymer (A) is obtained, a solution of the (meth) acrylic acid ester polymer (A) is added with a cross-linking agent (B), a white colorant (C), and optionally a diluting solvent. The active energy ray-curable component (D), the photopolymerization initiator (E), the additive and the like are added and sufficiently mixed to obtain a adhesive composition P (coating solution) diluted with a solvent. If any of the above components is in the form of a solid, or if precipitation occurs when the component is mixed with another component in an undiluted state, the component is used alone as a diluting solvent in advance. It may be dissolved or diluted and then mixed with other ingredients.

Examples of the diluting solvent include aliphatic hydrocarbons such as hexane, heptane and cyclohexane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride and ethylene chloride, methanol, ethanol, propanol and butanol. Alcohols such as 1-methoxy-2-propanol, ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone and cyclohexanone, esters such as ethyl acetate and butyl acetate, and cellosolve solvents such as ethyl cellosolve are used.

The concentration and viscosity of the coating solution prepared in this manner may be any range as long as it can be coated, and is not particularly limited and can be appropriately selected depending on the situation. For example, the adhesive composition P is diluted so as to have a concentration of 10 to 60% by mass. It should be noted that the addition of a diluting solvent or the like is not a necessary condition when obtaining the coating solution, and the diluting solvent may not be added as long as the adhesive composition P has a coatable viscosity or the like. In this case, the adhesive composition P becomes a coating solution using the polymerization solvent of the (meth) acrylic acid ester polymer (A) as it is as a diluting solvent.

(3) Formation of Adhesive Layer The pressure-sensitive adhesive layer 11 in the present embodiment is preferably made of a pressure-sensitive adhesive obtained by cross-linking the pressure-sensitive adhesive composition P (coating layer). Crosslinking of the adhesive composition P can usually be carried out by heat treatment. In addition, this heat treatment can also serve as a drying treatment when volatilizing the diluting solvent or the like from the coating layer of the adhesive composition P applied to the desired object.

The heating temperature of the heat treatment is preferably 50 to 150 ° C, particularly preferably 70 to 120 ° C. The heating time is preferably 10 seconds to 10 minutes, and particularly preferably 50 seconds to 2 minutes.

After the heat treatment, if necessary, a curing period of about 1 to 2 weeks may be provided at room temperature (for example, 23 ° C., 50% RH). If this curing period is required, the adhesive is formed after the curing period has elapsed, and if the curing period is not required, after the heat treatment is completed.

By the above heat treatment (and curing), the (meth) acrylic acid ester polymer (A) is sufficiently crosslinked via the crosslinking agent (B). The pressure-sensitive adhesive thus obtained can easily satisfy desired values such as gel fraction, storage elastic modulus, and pressure-sensitive adhesive strength, and is excellent in step followability under high temperature and high humidity conditions.

(4) Physical Properties of Adhesive (4-1) Gel Fraction The gel fraction of the adhesive constituting the adhesive layer 11 in the present embodiment is preferably 20% or more as a lower limit value, and is 30% or more. It is more preferably 40% or more, further preferably 48% or more, and most preferably 55% or more. When the lower limit of the gel fraction of the pressure-sensitive adhesive is the above, the cohesive force of the pressure-sensitive adhesive becomes high, and the step followability under high temperature and high humidity conditions becomes more excellent. The gel fraction of the pressure-sensitive adhesive according to the present embodiment is preferably 99% or less, more preferably 90% or less, particularly preferably 80% or less, and further 74. % Or less is preferable. When the upper limit of the gel fraction of the pressure-sensitive adhesive is the above, the pressure-sensitive adhesive does not become too hard, and both the initial step-following property and the step-following property under high temperature and high humidity conditions are excellent. In addition, good adhesive strength is exhibited, and the adhesiveness with the adherend becomes more excellent. Here, the method for measuring the gel fraction of the pressure-sensitive adhesive is as shown in a test example described later.

In the case of an active energy ray-curable pressure-sensitive adhesive, the gel fraction of the pressure-sensitive adhesive after active energy ray-curing is preferably 30% or more, more preferably 40% or more, and particularly 55%. The above is preferable, and more preferably 65% or more. The gel fraction is preferably 99% or less, more preferably 90% or less, particularly preferably 85% or less, and further preferably 80% or less as the upper limit value. .. When the gel fraction of the pressure-sensitive adhesive after the active energy ray curing is in the above range, the step followability under high temperature and high humidity conditions becomes more excellent. In addition, good adhesive strength is exhibited, and the adhesiveness with the adherend becomes more excellent.

(4-2) Storage Elastic Modulus The storage elastic modulus of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 11 in the present embodiment at 23 ° C. is preferably 0.001 MPa or more, particularly 0.01 MPa or more as a lower limit value. It is preferably 0.04 MPa or more, and most preferably 0.07 MPa or more. When the lower limit value of the storage elastic modulus is the above, the step followability under high temperature and high humidity conditions becomes excellent. The upper limit of the storage elastic modulus is preferably 3 MPa or less, particularly preferably 1 MPa or less, further preferably 0.5 MPa or less, and most preferably 0.2 MPa or less. .. When the upper limit value of the storage elastic modulus is the above, the initial step followability is excellent. The storage elastic modulus in the present specification is a value measured by the torsional shear method at a measurement frequency of 1 Hz in accordance with JIS K7244-6. Specifically, it is as shown in the test example described later.

In the case of an active energy ray-curable pressure-sensitive adhesive, the storage elastic modulus of the pressure-sensitive adhesive after active energy ray-curing at 23 ° C. is preferably 0.10 MPa or more as a lower limit value, and more preferably 0.15 MPa or more. It is preferable, particularly preferably 0.20 MPa or more, and further preferably 0.25 MPa or more. When the lower limit value of the storage elastic modulus is the above, the step followability under high temperature and high humidity conditions becomes excellent. The upper limit of the storage elastic modulus is preferably 5 MPa or less, particularly preferably 1 MPa or less, and further preferably 0.5 MPa or less. When the upper limit value of the storage elastic modulus is the above, the adhesiveness becomes excellent.

1-2. Peeling Sheets The peeling sheets 12a and 12b protect the pressure-sensitive adhesive layer 11 until the time when the pressure-sensitive adhesive sheet 1 is used, and are peeled off when the pressure-sensitive adhesive sheet 1 (the pressure-sensitive adhesive layer 11) is used. In the pressure-sensitive adhesive sheet 1 according to the present embodiment, one or both of the release sheets 12a and 12b are not always necessary.

Examples of the release sheets 12a and 12b include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, and polybutylene. Telephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene / (meth) acrylic acid copolymer film, ethylene / (meth) acrylic acid ester copolymer film, polystyrene film, polycarbonate film, polyimide film, fluorine A resin film or the like is used. In addition, these crosslinked films are also used. Further, these laminated films may be used.

It is preferable that the peeling surfaces (particularly the surfaces in contact with the pressure-sensitive adhesive layer 11) of the peeling sheets 12a and 12b are subjected to a peeling treatment. Examples of the release agent used in the release treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents. Of the release sheets 12a and 12b, it is preferable that one release sheet is a heavy release type release sheet having a large release force and the other release sheet is a light release type release sheet having a small release force.

The thickness of the release sheets 12a and 12b is not particularly limited, but is usually about 20 to 150 μm.

2. Physical Properties (1) Adhesive Strength The adhesive strength of the adhesive sheet 1 according to the present embodiment to soda lime glass is preferably 1N / 25mm or more, more preferably 5N / 25mm or more, and 10N / 25mm as a lower limit value. The above is particularly preferable, and 15 N / 25 mm or more is further preferable. When the lower limit of the adhesive force is the above, the step followability under high temperature and high humidity conditions becomes more excellent. The upper limit of the adhesive strength is preferably 70 N / 25 mm or less, more preferably 60 N / 25 mm or less, and particularly preferably 50 N / 25 mm or less. When the upper limit value of the adhesive force is the above, good reworkability can be obtained, and when a bonding error occurs, the display body constituent member, particularly an expensive display body constituent member can be reused.

When the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 11 is an active energy ray-curable pressure-sensitive adhesive, the adhesive strength of the pressure-sensitive adhesive sheet 1 according to the present embodiment to soda lime glass after irradiation with active energy rays is 5 N / 25 mm as a lower limit. The above is preferable, 10 N / 25 mm or more is more preferable, 20 N / 25 mm or more is particularly preferable, and 25 N / 25 mm or more is further preferable. When the lower limit of the adhesive force is the above, the step followability under high temperature and high humidity conditions becomes more excellent. The upper limit of the adhesive strength is preferably 70 N / 25 mm or less, more preferably 60 N / 25 mm or less, and particularly preferably 50 N / 25 mm or less. When the upper limit value of the adhesive force is the above, good reworkability can be obtained, and when a bonding error occurs, the display body constituent member, particularly an expensive display body constituent member can be reused.

Here, the adhesive strength in the present specification basically means the adhesive strength measured by the 180-degree peeling method according to JIS Z0237: 2009, but the measurement sample is 25 mm wide and 100 mm long, and the measurement sample is used. It is attached to an adherend, pressurized at 0.5 MPa and 50 ° C. for 20 minutes, left at normal pressure, 23 ° C. and 50% RH for 24 hours, and then measured at a peeling speed of 300 mm / min. It shall be. The adhesive strength after irradiation with the active energy ray is assumed to be the adhesive strength of the pressure-sensitive adhesive layer cured by irradiation with the active energy ray after the adherend is attached.

(2) Step-following rate With respect to the step-following property under high-temperature and high-humidity conditions, the adhesive layer 11 preferably has a step-following rate (%) represented by the following formula of 5% or more, preferably 10% or more. It is more preferably 20% or more, further preferably 30% or more, and most preferably 40% or more. As a result, it can be said that the step followability under high temperature and high humidity conditions is excellent, and in that case, the step followability at the initial stage (at the time of bonding) is also excellent. The upper limit of the step follow-up rate is not particularly limited, but is usually preferably 80% or less, and particularly preferably 70% or less.
Step follow-up rate (%) = {(height of step (μm) maintained in a buried state without air bubbles, floating, peeling, etc. after a predetermined durability test) / (thickness of adhesive layer)} × 100
The test method for the step follow-up rate is as shown in a test example described later. Further, for the active energy ray-curable pressure-sensitive adhesive layer, it is assumed that the step follow-up rate of the pressure-sensitive adhesive layer cured by irradiation with active energy rays after the adherend is attached.

3. 3. Production of Adhesive Sheet As an example of production of the adhesive sheet 1, the coating solution of the adhesive composition P is applied to the peeling surface of one of the release sheets 12a (or 12b) and heat-treated to perform the adhesive composition. After P is thermally crosslinked to form a coating layer, the peeling surface of the other release sheet 12b (or 12a) is superposed on the coating layer. When the curing period is required, the curing period is set, and when the curing period is not required, the coating layer becomes the adhesive layer 11 as it is. As a result, the adhesive sheet 1 is obtained. The conditions for heat treatment and curing are as described above.

As another production example of the pressure-sensitive adhesive sheet 1, the coating solution of the pressure-sensitive adhesive composition P is applied to the peel-off surface of one of the release sheets 12a, heat-treated to heat-crosslink the pressure-sensitive adhesive composition P, and then coated. A layer is formed to obtain a release sheet 12a with a coating layer. Further, the coating solution of the adhesive composition P is applied to the peeling surface of the other release sheet 12b, heat treatment is performed to thermally crosslink the adhesive composition P to form a coating layer, and the coating layer is attached. To obtain the release sheet 12b of. Then, the release sheet 12a with the coating layer and the release sheet 12b with the coating layer are bonded so that both coating layers are in contact with each other. Here, a plurality of release sheets with a coating layer may be prepared, and a desired number of the coating layers may be bonded together. When the curing period is required, the curing period is set, and when the curing period is not required, the laminated coating layer becomes the pressure-sensitive adhesive layer 11. As a result, the adhesive sheet 1 is obtained. According to this production example, even when the pressure-sensitive adhesive layer 11 is thick, stable production is possible.

As a method for applying the coating solution of the adhesive composition P, for example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method and the like can be used.

[Display body]
Examples of the type of display body (display) according to the present embodiment include display bodies such as televisions, monitors for personal computers, monitors of various devices, digital signage, smartphones, and tablet terminals. These display bodies may be required to be in harmony with the appearance of white peripheral members such as a white frame material, a white wall, and a white printed portion. However, the display body according to the present invention is not limited to these.

As shown in FIG. 2, the display body 2 according to the present embodiment includes a first display body constituent member 21 (one display body constituent member) and a second display body constituent member 22 (another display body constituent member). ) And an adhesive layer 11 located between them and for sticking the first display body constituent member 21 and the second display body constituent member 22 to each other.

At least one of the first display body constituent member 21 and the second display body constituent member 22 may have a step on the surface on the side to be bonded by the pressure-sensitive adhesive layer 11. In the present embodiment shown in FIG. 2, the first display body component 21 has a step such as a printing layer 3 on the surface on the adhesive layer 11 side.

The pressure-sensitive adhesive layer 11 in the display body 2 is formed from the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 described above. Specifically, the pressure-sensitive adhesive layer 11 in the display body 2 may be the pressure-sensitive adhesive layer 11 itself of the pressure-sensitive adhesive sheet 1, or the pressure-sensitive adhesive layer 11 may be an active energy ray-cured product.

Examples of the display body 2 include a liquid crystal display (LCD), a light emitting diode (LED) display, an organic electroluminescence (organic EL) display, electronic paper, and the like, and may be a touch panel. Further, it may be a member constituting a part thereof.

The first display body constituent member 21 is preferably a protective panel made of a glass plate, a plastic plate, or the like, or a laminated body containing them. In this case, the print layer 3 is generally formed in a frame shape on the pressure-sensitive adhesive layer 11 side of the first display body constituent member 21.

The glass plate is not particularly limited, and for example, chemically strengthened glass, non-alkali glass, quartz glass, soda lime glass, barium / strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, barium borosilicate. Examples include glass. The thickness of the glass plate is not particularly limited, but is usually 0.1 to 5 mm, preferably 0.2 to 2 mm.

The plastic plate is not particularly limited, and examples thereof include an acrylic plate and a polycarbonate plate. The thickness of the plastic plate is not particularly limited, but is usually 0.2 to 5 mm, preferably 0.4 to 3 mm.

Various functional layers (transparent conductive film, metal layer, silica layer, hard coat layer, antiglare layer, etc.) may be provided on one side or both sides of the glass plate or the plastic plate, or an optical member. May be laminated. Further, the transparent conductive film and the metal layer may be patterned.

The second display body constituent member 22 is an optical member to be attached to the first display body constituent member 21, a display body module (for example, a liquid crystal module, a light emitting diode (LED) module, an organic electroluminescence (organic EL) module). Etc.), or a laminated body including a display module.

Examples of the optical member include a shatterproof film, a polarizing film, a retardation film, a viewing angle compensation film, a brightness improving film, a contrast improving film, a liquid crystal polymer film, a diffusion film, a transflective reflective film, a transparent conductive film, and a film. Examples include sensors. Examples of the shatterproof film include a hard coat film in which a hard coat layer is formed on one side of the base film.

The color of the print layer 3 in this embodiment is preferably white. The material constituting the print layer 3 is not particularly limited, and a known material for printing is used. The thickness of the print layer 3, that is, the lower limit of the height of the step is preferably 3 μm or more, more preferably 5 μm or more, particularly preferably 7 μm or more, and most preferably 10 μm or more. preferable. When the lower limit value is equal to or higher than the above value, it is possible to sufficiently secure concealment such as making the electrical wiring invisible to the viewer. The upper limit is preferably 200 μm or less, more preferably 100 μm or less, and particularly preferably 30 μm or less. When the upper limit value is equal to or less than the above value, it is possible to prevent deterioration of the step followability of the pressure-sensitive adhesive layer 11 with respect to the printing layer 3.

In order to manufacture the display body 2, as an example, one of the release sheets 12a of the pressure-sensitive adhesive sheet 1 is peeled off, and the exposed pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 is separated from the printed layer of the first display body component 21. It is affixed to the surface on the side where 3 exists.

After that, the other release sheet 12b is peeled from the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1, and the exposed pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 and the second display body constituent member 22 are bonded together. Further, as another example, the bonding order of the first display body constituent member 21 and the second display body constituent member 22 may be changed.

When the pressure-sensitive adhesive layer 11 is inactive energy ray-curable, after the first display body component 21 and the second display body component 22 are bonded to each other via the pressure-sensitive adhesive layer 11 as described above, The pressure-sensitive adhesive layer 11 is irradiated with active energy rays. As a result, the energy ray-curable component (D) in the pressure-sensitive adhesive layer 11 is polymerized, and the pressure-sensitive adhesive layer 11 is cured. The pressure-sensitive adhesive layer 11 is usually irradiated with energy rays through either the first display body component 21 or the second display body component 22, preferably the first display body as a protective panel. This is done through the component 21.

The active energy ray refers to an electromagnetic wave or a charged particle beam having an energy quantum, and specific examples thereof include ultraviolet rays and electron beams. Among the active energy rays, ultraviolet rays, which are easy to handle, are particularly preferable.

Irradiation of ultraviolet rays, a high-pressure mercury lamp, a fusion H lamp, can be carried out by a xenon lamp or the like, the dose of ultraviolet ray is preferably illuminance is 50~1000mW / cm ² approximately, 100~500mW / cm ² of about Is preferable. Further, the light quantity is preferably 50~10000mJ / cm ^2, more preferably 200~7000mJ / cm ^2, and particularly preferably 500~3000mJ / cm ^2. On the other hand, the irradiation of the electron beam can be performed by an electron beam accelerator or the like, and the irradiation amount of the electron beam is preferably about 10 to 1000 grad.

Here, as shown in FIG. 3, the display body 2 according to the present embodiment may have a white frame member 4 on the peripheral edge of the display body 2.

In the display body 2, the physical properties of the pressure-sensitive adhesive layer 11 described above give a sense of unity with the white frame material 4, and have excellent appearance harmony. Further, the display body 2 ensures visibility as a display body.

Further, in the display body 2, when the pressure-sensitive adhesive layer 11 is formed from the pressure-sensitive adhesive composition P, the pressure-sensitive adhesive layer 11 is excellent in step-following property under high temperature and high humidity conditions, so that the display body 2 However, even when the product is placed under high temperature and high humidity conditions (for example, 85 ° C., 85% RH), it is possible to prevent bubbles, floats, peeling, etc. from occurring in the vicinity of the step.

The embodiments described above are described for facilitating the understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

For example, either or both of the release sheets 12a and 12b in the pressure-sensitive adhesive sheet 1 may be omitted, and desired optical members may be laminated in place of the release sheets 12a and / or 12b. Further, the first display body constituent member 21 may not have a step. Further, not only the first display body constituent member 21 but also the second display body constituent member 22 may have a step on the adhesive layer 11 side.

Hereinafter, the present invention will be described in more detail with reference to Examples and the like, but the scope of the present invention is not limited to these Examples and the like.

[Example 1]
1. 1. Preparation of (meth) acrylic acid ester polymer 70 parts by mass of 2-ethylhexyl acrylate, 15 parts by mass of methyl methacrylate, and 15 parts by mass of 2-hydroxyethyl acrylate are copolymerized by a solution polymerization method to obtain (meth) acrylic. The acid ester polymer (A) was prepared. When the molecular weight of this (meth) acrylic acid ester polymer (A) was measured by the method described later, the weight average molecular weight (Mw) was 700,000.

2. Preparation of Adhesive Composition 100 parts by mass (solid content conversion value; the same applies hereinafter) of the (meth) acrylic acid ester polymer (A) obtained in the above step 1 and a trimethylolpropane-modified bird as a cross-linking agent (B). 0.2 parts by mass of range isocyanate (manufactured by Toyochem Co., Ltd., product name "BHS8515"), 1.0 part by mass of titanium oxide-based colorant as white colorant (C), and 3-glycid as silane coupling agent. A coating solution of the adhesive composition was obtained by mixing 0.2 parts by mass of xypropyltrimethoxysilane, stirring thoroughly, and diluting with methyl ethyl ketone.

Here, Table 1 shows each formulation (solid content conversion value) of the adhesive composition when the (meth) acrylic acid ester polymer (A) is 100 parts by mass (solid content conversion value). Details of the abbreviations and the like shown in Table 1 are as follows.
[(Meta) Acrylic Ester Polymer (A)]
2EHA: 2-ethylhexyl acrylate MMA: methyl methacrylate HEA: 2-hydroxyethyl acrylate IBXA: isobornyl acrylate ACMO: N-acryloylmorpholin BA: n-butyl acrylate AA: acrylic acid
[Crosslinking agent (B)]
TDI: Trimethylolpropane-modified tolylene diisocyanate (manufactured by Toyochem, product name "BHS8515")
XDI: Trimethylolpropane-modified xylylene diisocyanate (manufactured by Soken Chemical Co., Ltd., product name "TD-75")

The composition of the titanium oxide-based colorant as the white colorant (C) was 91.2% by mass of titanium oxide, 0.8% by mass of zinc oxide, and 8% by mass of silica. The mode diameter of the titanium oxide-based colorant was 420 nm, and the median diameter was 420 nm. The particle size was measured by the dynamic light scattering method (manufactured by MicrotracBEL, device name: Nanotrac Wave was used).

3. 3. Manufacture of Adhesive Sheet A heavy release type release sheet (manufactured by Lintec Corporation, product name "SP-PET752150") in which one side of a polyethylene terephthalate film is peeled off with a silicone-based release agent from the coating solution of the adhesive composition obtained in step 2 above. ”) Was applied to the peeled surface with a knife coater. Then, the coating layer was heat-treated at 90 ° C. for 1 minute to form a coating layer (thickness: 50 μm), thereby producing a heavy peeling type release sheet with a coating layer.

On the other hand, a light peeling type release sheet (manufactured by Lintec Corporation, product name "SP-PET382120") obtained by peeling one side of a polyethylene terephthalate film with a silicone-based release agent from the coating solution of the adhesive composition obtained in the above step 2. It was applied to the peeled surface of the above with a knife coater. Then, the coated layer was heat-treated at 90 ° C. for 1 minute to form a coated layer (thickness: 50 μm) to prepare a light peeling type release sheet with a coated layer.

The surface on the coating layer side of the heavy peeling type release sheet with the coating layer obtained above and the surface on the coating layer side of the light peeling type release sheet with the coating layer obtained above are bonded to each other to obtain a thickness. A laminated body in which a 100 μm coating layer was sandwiched between a heavy-release type release sheet and a light-release type release sheet was obtained.

Then, the laminate is cured under the conditions of 23 ° C. and 50% RH for 7 days to obtain an adhesive having a structure of a heavy release type release sheet / adhesive layer (thickness: 100 μm) / light release type release sheet. Manufactured the sheet.

The thickness of the pressure-sensitive adhesive layer is a value measured using a constant pressure thickness measuring device (manufactured by Teclock Co., Ltd., product name "PG-02") in accordance with JIS K7130.

[Examples 2 to 10, Comparative Examples 1 and 2]
Types and proportions of each monomer constituting the (meth) acrylic acid ester polymer (A), weight average molecular weight (Mw) of the (meth) acrylic acid ester polymer (A), type of cross-linking agent (B), white coloring A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the blending amount of the agent (C) and the thickness of the pressure-sensitive adhesive layer were changed as shown in Table 1. However, in Examples 6 to 9, ε-caprolactone-modified tris- (2-acryloxyethyl) isocyanurate as the active energy ray-curable component (D) (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "NK ester A-9300"). -1CL ") 5 parts by mass and 0.5 parts by mass of 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide as the photopolymerization initiator (E) were further blended to prepare an adhesive composition. The adhesive composition was used to form an active energy ray-curable pressure-sensitive adhesive layer. The thickness of the pressure-sensitive adhesive layer was changed by changing the thickness of the pressure-sensitive adhesive layer formed on the release sheet and the number of layers.

The above-mentioned weight average molecular weight (Mw) is a polystyrene-equivalent weight average molecular weight measured under the following conditions (GPC measurement) using gel permeation chromatography (GPC).
<Measurement conditions>
-GPC measuring device: HLC-8020 manufactured by Tosoh Corporation
-GPC column (passed in the following order): TSK guard volume HXL-H manufactured by Tosoh Corporation
TSK gel GMHXL (x2)
TSK gel G2000HXL
-Measurement solvent: tetrahydrofuran-Measurement temperature: 40 ° C

[Test Example 1] (Measurement of gel fraction)
The adhesive sheets obtained in Examples and Comparative Examples were cut into a size of 80 mm × 80 mm, the adhesive layer was wrapped in a polyester mesh (mesh size 200), the mass was weighed with a precision balance, and the above mesh was used. The mass of the pressure-sensitive adhesive alone was calculated by subtracting the mass of a single substance. The mass at this time is M1.

Next, the pressure-sensitive adhesive wrapped in the polyester mesh was immersed in ethyl acetate at room temperature (23 ° C.) for 24 hours. Then, the adhesive was taken out, air-dried for 24 hours in an environment of a temperature of 23 ° C. and a relative humidity of 50%, and further dried in an oven at 80 ° C. for 12 hours. After drying, the mass was weighed with a precision balance, and the mass of the adhesive alone was calculated by subtracting the mass of the mesh alone. The mass at this time is M2. The gel fraction (%) is represented by (M2 / M1) × 100. As a result, the gel fraction of the pressure-sensitive adhesive (before UV irradiation) was derived. The results are shown in Table 2.

On the other hand, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheets obtained in Examples 6 to 9 was irradiated with active energy rays (ultraviolet rays; UV) under the following conditions through the light-release type release sheet to cure the pressure-sensitive adhesive layer. I let you. For the pressure-sensitive adhesive in this cured pressure-sensitive adhesive layer, the gel fraction (after UV irradiation) was derived in the same manner as above. The results are shown in Table 2.

<Activation energy ray irradiation conditions>
・ Uses high-pressure mercury lamp ・ Illuminance 200mW / cm ² , light intensity 2000mJ / cm ²
・ UV illuminance / photometer uses "UVPF-A1" manufactured by iGraphics.

[Test Example 2] (Measurement of L * a * b *)
The light release type release sheet was peeled from the adhesive sheets obtained in Examples and Comparative Examples, and the exposed adhesive layer was attached to a soda lime glass plate (manufactured by Nippon Sheet Glass Co., Ltd.). Next, the heavy-release type release sheet was peeled off from the pressure-sensitive adhesive layer, and the exposed pressure-sensitive adhesive layer was laminated with a polymethyl methacrylate resin layer on a polycarbonate resin plate (manufactured by Mitsubishi Gas Chemical Company, Inc., product name " The surface of the Iupilon sheet MR58U (thickness: 1 mm) on the polycarbonate resin plate side was attached, and this was used as a sample.

A simultaneous photometric spectroscopic chromaticity meter (manufactured by Nippon Denshoku Kogyo Co., Ltd., product name "SQ2000") was used on the surface of the obtained sample on the plastic plate side, and the reflected light was CIE1976L * a * b * color system. The brightness L * (L * M), the chromaticity a * (a * M), and the chromaticity b * (b * M) defined by the above were measured. Further, from the above results, the color difference ΔE * was calculated by the following formula (I). The results are shown in Table 2.

[Test Example 3] (Measurement of total light transmittance)
The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples was bonded to glass, and this was used as a measurement sample. After performing background measurement with glass, all light rays of the above measurement sample were measured using a haze meter (manufactured by Nippon Denshoku Kogyo Co., Ltd., product name "NDH-5000") in accordance with JIS K7361-1: 1997. The transmittance (%) was measured. The results are shown in Table 2.

[Test Example 4] (Measurement of haze value)
The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples was bonded to glass, and this was used as a measurement sample. After performing background measurement with glass, the haze value (all) of the above measurement sample using a haze meter (manufactured by Nippon Denshoku Kogyo Co., Ltd., product name "NDH-5000") according to JIS K7136: 2000. The ray haze value;%) was measured. The results are shown in Table 2.

[Test Example 5] (Measurement of storage elastic modulus)
The release sheet was peeled off from the adhesive sheets obtained in Examples and Comparative Examples, and a plurality of adhesive layers were laminated so as to have a thickness of 3 mm. A cylinder (height 3 mm) having a diameter of 8 mm was punched out from the obtained laminated body of the pressure-sensitive adhesive layer, and this was used as a sample.

For the above sample, the storage elastic modulus (MPa; before UV irradiation) was determined by the torsional shear method using a viscoelasticity measuring device (manufactured by Physica, product name "MCR300") in accordance with JIS K7244-6 under the following conditions. It was measured. The results are shown in Table 2.
Measurement frequency: 1Hz
Measurement temperature: 23 ° C

Further, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheets obtained in Examples 6 to 9 was irradiated with active energy rays (ultraviolet rays; UV) under the same conditions as in Test Example 1 through the light-release type release sheet to adhere. The agent layer was cured. For the pressure-sensitive adhesive of this cured pressure-sensitive adhesive layer, the storage elastic modulus (after UV irradiation) was derived in the same manner as described above. The results are shown in Table 2.

[Test Example 6] (Measurement of adhesive strength)
The light release type release sheet is peeled off from the adhesive sheets obtained in Examples and Comparative Examples, and the exposed adhesive layer is a polyethylene terephthalate (PET) film having an easy adhesive layer (manufactured by Toyo Spinning Co., Ltd., product name "PET A4300"). , Thickness: 100 μm), and a laminated body of a heavy peeling type release sheet / adhesive layer / PET film was obtained. The obtained laminate was cut into a width of 25 mm and a length of 100 mm, and this was used as a sample.

In an environment of 23 ° C. and 50% RH, the heavy-release type release sheet is peeled off from the above sample, the exposed adhesive layer is attached to soda lime glass (manufactured by Nippon Sheet Glass Co., Ltd.), and then the autoclave manufactured by Kurihara Seisakusho Co., Ltd. is used. The pressure was increased at 0.5 MPa and 50 ° C. for 20 minutes. Then, it was left for 24 hours under the condition of 23 ° C. and 50% RH.

Next, using a tensile tester (manufactured by Orientec, product name "Tencilon"), the adhesive strength (before UV irradiation; N / 25 mm) was measured under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180 degrees. Conditions other than those described here were measured in accordance with JIS Z0237: 2009. The results are shown in Table 2.

In Examples 6 to 9, after the pressure-sensitive adhesive layer was attached to the soda lime glass in the same manner as above, the PET film was irradiated with active energy rays under the same conditions as in Test Example 1 to form the pressure-sensitive adhesive layer. The adhesive strength after curing (after UV irradiation) was also measured. The results are shown in Table 2.

[Test Example 7] (Measurement of step follow-up rate)
On the surface of a glass plate (manufactured by NSG Precision Co., Ltd., product name "Corning Glass Eagle XG", length 90 mm x width 50 mm x thickness 0.5 mm), UV curable ink (manufactured by Teikoku Inks, product name "POS-911 ink") ) Was screen-printed with a predetermined thickness in a frame shape (outer shape: length 90 mm × width 50 mm, width 5 mm). Next, the printed ultraviolet curable ink is cured by irradiating with ultraviolet rays (80 W / cm ² , 2 metal halide lamps, lamp height 15 cm, belt speed 10 to 15 m / min), and a step (height of the step) due to printing is cured. A stepped glass plate having one of 110 μm, 30 μm, 15 μm, 12.5 μm, 10 μm, 7.5 μm, and 5 μm) was prepared.

The light release type release sheet is peeled off from the adhesive sheets obtained in Examples and Comparative Examples, and the exposed adhesive layer is a polyethylene terephthalate (PET) film having an easy adhesive layer (manufactured by Toyobo Co., Ltd., product name "PET A4300", It was bonded to an easy-adhesion layer having a thickness (thickness: 100 μm). Next, the heavy-release type release sheet is peeled off to expose the pressure-sensitive adhesive layer, and using a laminator (manufactured by Fujipla, product name "LPD3214"), each step is provided so that the pressure-sensitive adhesive layer covers the entire surface of the frame-shaped print. Laminated on a glass plate. Then, it was autoclaved for 20 minutes under the conditions of 50 ° C. and 0.5 MPa, and left at normal pressure at 23 ° C. and 50% RH for 24 hours.

In Examples 6 to 9, the PET film was irradiated with active energy rays under the same conditions as in Test Example 1 to cure the pressure-sensitive adhesive layer. Then, it was stored for 72 hours under high temperature and high humidity conditions of 85 ° C. and 85% RH (durability test). Then, the step followability was evaluated as the step follow rate (%) represented by the following formula. The results are shown in Table 2.
Step follow-up rate (%) = {(height of step (μm) maintained in a buried state without air bubbles, floating, peeling, etc. after durability test) / (thickness of adhesive layer)} × 100

[Test Example 8] (Evaluation of black concealment and appearance harmony)
The adhesive sheets obtained in Examples and Comparative Examples were cut into a length of 70 mm × a width of 70 mm, and the adhesive layer of the adhesive sheet was formed into two soda lime glass plates (manufactured by Nippon Sheet Glass Co., Ltd., length 70 mm × width 70 mm × thickness). It was attached so as to be sandwiched between them (1.1 mm), and this was used as a sample. In Examples 6 to 9, one of the soda lime glass plates was irradiated with active energy rays under the same conditions as in Test Example 1 to cure the pressure-sensitive adhesive layer, and this was used as a sample.

The obtained sample was printed on the display portion (black) and the frame-shaped white print on the tablet terminal (manufactured by Apple Inc., product name "iPad (registered trademark)", pixel density: 264 ppi, with frame-shaped white print portion). It was laminated on the entire surface including both parts. Then, the black concealment and appearance harmony were visually evaluated for the sample based on the following criteria. The results are shown in Table 2.

<Evaluation criteria for black concealment>
◎… It was white regardless of the viewing angle, and the black color of the display could not be perceived at all.
〇… It was white when observed from an oblique direction, and the black color of the display could not be perceived at all, but the black color of the display could be slightly perceived when observed from the front.
Δ… It is certain that the black color of the display is suppressed, but the black color of the display could be perceived even when observed from an oblique direction.
×… The black color of the display remained strong even when observed from an oblique direction.

<Evaluation criteria for appearance harmony>
◎… It was difficult to see the boundary between the display part of the tablet terminal and the white print part regardless of the viewing angle.
◯… In frontal observation, it was difficult to visually recognize the boundary between the display portion of the tablet terminal and the white print portion, but the boundary could be sufficiently visually recognized depending on the viewing angle.
Δ: The boundary between the display portion and the white print portion of the tablet terminal was visually visible even in the frontal observation, but the effect of providing the sample was confirmed.
X ... Even in the frontal observation, there was no change in the visibility of the boundary between the display portion and the white print portion of the tablet terminal when the sample was not provided.

[Test Example 9] (Evaluation of visibility)
On a display with a size of 15.6 inches and a resolution of 1366 x 768 (manufactured by Fujitsu Limited, product name "LITEBOOK A574 / H"), various characters in black on a white background (font: MS P Gothic; "A" to "N", "A" to "Z" and "0" to "9") were displayed 100% with a size of 10.5 points.

The sample obtained in Test Example 8 was placed on the display. Then, at a position 50 cm from the display, it was confirmed visually whether the characters could be read, and the visibility was evaluated according to the following criteria. The results are shown in Table 2.
⊚: All characters were readable.
◯: Some characters could not be read depending on the type of characters.
×: Most of the characters could not be read.

As can be seen from Table 2, the one using the adhesive sheet obtained in the examples was excellent in black concealment property, appearance harmony with the white body, and visibility.

The adhesive sheet of the present invention can be suitably used for bonding display body constituent members to each other, for example, in a display body having a white frame material or a display body hung on a white wall.

1 ... Adhesive sheet 11 ... Adhesive layer 12a, 12b ... Peeling sheet 2 ... Display body 21 ... First display body component 22 ... Second display body component 3 ... Printing layer 4 ... Frame material

Claims (10)

An adhesive sheet provided with an adhesive layer for adhering one display body component and another display body component.
The color difference ΔE * from the completely white color of the pressure-sensitive adhesive layer defined by the CIE1976L * a * b * color system is less than 95.
A pressure-sensitive adhesive sheet having a total light transmittance of 10% or more of the pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheet according to claim 1, wherein the haze value of the pressure-sensitive adhesive layer is 0.5% or more and 100% or less. The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the pressure-sensitive adhesive layer is made of a pressure-sensitive adhesive containing a white colorant. The pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein the content of the white colorant in the pressure-sensitive adhesive is 0.01% by mass or more and 50% by mass or less. The pressure-sensitive adhesive sheet according to any one of claims 1 to 4, wherein the pressure-sensitive adhesive is an acrylic pressure-sensitive adhesive. The claim is characterized in that the pressure-sensitive adhesive is a cross-linked adhesive composition containing at least a (meth) acrylic acid ester polymer (A), a cross-linking agent (B) and a white colorant (C). The adhesive sheet according to any one of 1 to 5. Two release sheets and
The pressure-sensitive adhesive sheet according to any one of claims 1 to 6, further comprising the pressure-sensitive adhesive layer sandwiched between the two release sheets so as to be in contact with the peel-off surfaces of the two release sheets. One display body component and
With other display body components,
A display body including the one display body component and an adhesive layer for adhering the other display body components to each other.
A display body characterized in that the pressure-sensitive adhesive layer is formed from the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to any one of claims 1 to 7. The display body according to claim 8, wherein at least one of the display body component and the other display body component has a step on the surface on the side to be bonded by the pressure-sensitive adhesive layer. The display body according to claim 8 or 9, wherein the display body has a white peripheral member.

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